PHILADELPHIA – The American Civil Liberties Union will argue in federal appeals court tomorrow that the Constitution requires law enforcement to get a warrant from a judge before tracking people's cars with GPS devices.

In the case, the FBI – without a warrant – attached a GPS tracker to the vehicle of three men suspected of burglarizing pharmacies. Following the January 2012 Supreme Court ruling that doing so constitutes a "search" under the Fourth Amendment, the district court issued a decision suppressing the evidence produced by the location tracking.

The Justice Department appealed that ruling to the Third Circuit Court of Appeals, arguing in part that even though attaching the device is a search, a warrant is not needed because of a rule called the "automobile exception." The ACLU filed a friend-of-the-court brief supporting the lower court's opinion, joined by the ACLU of Pennsylvania, the Electronic Frontier Foundation, and the National Association of Criminal Defense Lawyers.

"Just because a technology wasn't around when the Constitution was written doesn't mean that it's not covered," said Catherine Crump, the ACLU attorney who will argue Tuesday before a three-judge panel. "The fundamental privacy rights established by the Fourth Amendment require that police justify their actions and show probable cause to a judge before they can conduct invasive surveillance like constant location tracking. The 'automobile exception' was created so police could find contraband hidden in cars, not so they could monitor a person's movements nonstop for days or even months on end."